Complications of an operation for Parkinson's disease

Published online 30 May 2010

Mohammed Yahia

Severe Parkinson's disease is sometimes treated by deep brain stimulation (DBS) of the subthalamic nucleus (STN). The surgery leads to a decrease in dopaminergic treatment among patients with the disease. However, some patients experience complications afterwards, including apathy and depression.

A group of researchers, including Rachid Hassani from Morocco, conducted a prospective study on the occurrence of apathy in the year following STN DBS. The study included 63 patients with Parkinson's disease who underwent the operation and then decreased their dopamine medication by 82% within 2 weeks. More than one-half of these patients developed apathy within 6 months, and almost one-half of those with apathy also developed depression. These complications were usually treatable by the end of the year.

The paper explains that non-motor fluctuations (which include neuropsychiatric, dysautonomic and sensory symptoms) in everyday life lead to a 2.5-fold increase in the risk of developing postoperative apathy and depression, making their presence the main predictor of these complications. Non-motor fluctuations were characterized by a lower density of dopaminergic receptors, especially in the mesocorticolimbic system in the brain. Coupled with the decrease in dopamine medication after the STN DBS surgery, this led the patients to develop hypodopaminergic symptoms, which include apathy and depression.

The study suggests that the presence of non-motor fluctuations shows a pattern in which such patients are probably more at risk of developing complications postoperatively. The researchers stress that it is important to monitor for apathy and depression after the surgery, and to treat patients who develop them with dopamine medication, in order to prevent severe depression and suicide, which are the most important complications of STN DBS.